Cellular telephones, commonly called a "cell", are widely used in America and there are many companies and plans to choose from.
The American system is for the standard GSM on 1900. Most companies offer deals to buy a cell phone for a penny or for free, but they almost always come with a one-to-three year obligation and a monthly bill that may not be in your best interest.
Expect to pay around $40-80 a month depending on your plan and how much time you spend on the phone. "Texting", or sending typed messages is becoming increasing popular and is almost always included in a plan, but check how many minutes are available a month on your plan because overages are expensive. It is important to understand all the details of the contract before signing.
Prepaid phones can also be purchased for a small price and then you must purchase minutes.